Danny R

Replaced the Fuel pump driver control module and reprogrammed the ECM with all the current updates and now I'm back in business. Even seems to be a little stronger and a little less noisy! Thanks for all the advice. Lesson learned. I'm into it for about $500 cuz i replaced the in tank fuel pump first but I'm not complaining. Would have been way more at the dealership!

Installed the new lift pump and I still have the same issue. What fuel pressure should I be seeing at idle on the low pressure side and the high pressure side and also how high does the high pressure side run at speeds? I do have a fuel pump driver module on order. Should have tried that first cuz it's a third of the price of the fuel pump but I was just following diagnostic procedures.

Thanks. No warranty but thats a story for another day. Im gonna need to find some troubleshooting procedures to determine if its module or lift pump but I think I have a source for that. I'll update next week when I get back on it.

My 2018 GMC 2500 Denali 2500 Duramax L5P Has 2 codes. P129F & P228C. It still runs but you have to feather the throttle to get it up to speed. It also goes into a reduced power mode. I have read that there may be some wiring issues to the lift pump. It seams that the lift pump is making a strange noise during the initial key on 30 second run time. I have also read up on the lift pump but it is some kind of 3 phase variable speed pump that I am not familiar with. Any info will be appreciated. My truck has 20K miles on it. and has not given me any issues up to now. No mods have been done to it.

2018 GMC.docx